Agricultural vacuum planters employ a plurality of row planters, each featuring a seed metering unit which relies on a seed disk rototably mounted within a housing in order to convey seeds individually from a respective seed hopper into a seeding chute that reaches down between a pair of furrowing disks in order to deliver the seed into a furrow opened in the ground by these furrowing disks. Inside the housing of the metering unit, the seed disk divides the housing interior into two sides, a vacuum side to which a vacuum pump is coupled to induce a low pressure state on this side of the disk, and a seed side having a seed chamber into which seed falls from the hopper via a supply chute coupled between the hopper and the seed unit. The housing of the metering unit has two hinged together halves that enclose the respective sides of the housing interior when closed together, while enabling opening of the housing to allow installation, inspection, removal, replacement, etc. of the seed disk. The seed disk has a plurality of apertures passing axially through it near the outer periphery of the disk at equally spaced positions disposed circumferentially around the central rotational axis of the disk. The vacuum source acting on the vacuum side of the disk pulls an individual seed into the open end of each aperture on the seed side of the disk as the aperture moves through the seed chamber under rotation of the seed disk, whereupon continued rotation of the seed disk then conveys the seed to the inlet of the seeding chute, where the seed falls through the seeding chute and into the furrow.
John Deere is a well-known manufacturer of such vacuum metered planters. One example of a seed metering unit and associated seed disk for a John Deere planter is disclosed in U.S. Pat. No. 6,932,236 of Ven Huizen, the entirey of which is incorporated herein by reference. The Huizen patent concerns a particular seed disk design and associated double eliminator and knockout assembly for improving the efficiency of a John Deere planter when planting corn seed.
Most commercially available seed disks have been designed for sunflower, cotton, soybean, sorghum, sugar beets, popcorn, sweet corn, and corn seed. Applicant previously planted canola seed used commercially available sugar beet seed disks on a John Deere planter, but found that the resulting performance was far from optimal. One notable problem was the lack of ‘singulation’, i.e. the conveyance of only a singular seed by each disk aperture. The tear-drop shaped apertures in the sugar beet disks had a tendency to pick up more than one canola seed in a single aperture.
Accordingly, there remained a need for a seed disk particularly suitable for use with canola seed, based on which Applicant undertook the development of the present invention to solve the shortcomings of the prior art in relation to planting of canola seed using a vacuum planter.